1. Field of the Invention
The present invention relates to engine speed controls and, more specifically, to a linkage assembly for an engine speed control.
2. Description of the Related Art
Small gasoline engines are often used with small recreational vehicles such as go-carts and mini-bikes. Such vehicles generally include a user-operated speed control mechanism such as a foot operated accelerator or a hand operated rotatable grip. Such vehicles are oftentimes operated at full throttle during nearly the entire time the vehicle is operated. For example, the operator of a go-cart may fully depress the foot accelerator during the entire time that the vehicle is being operated.
Such vehicles may also include a centrifugal clutch which engages when the engine reaches a predetermined engagement speed or rpm and disengages when the engine speed falls below the predetermined engagement speed. The idle speed of the engine must be below the predetermined engagement speed to allow the clutch to disengage when the vehicle is idling.
The present invention provides a linkage assembly which may be used with a vehicle for controlling the speed of the vehicle. The linkage assembly includes first linkage body and a second linkage body wherein the first linkage body is operably coupled to a user operable input mechanism and the second linkage body is operably coupled to the engine for controlling the speed thereof. The first and second linkage bodies are relatively moveable in a manner which allows the idle and maximum engine speeds defined by the linkage assembly to be set or adjusted without requiring an adjustment in the range of motion of the user operable input mechanism.
The invention comprises, in one form thereof, a vehicle having a vehicle body, an engine mounted on the vehicle body and a user-operable speed control assembly operably coupled to the engine wherein the speed control assembly selectively varies the speed of the engine. The speed control assembly includes a user-operable input mechanism having a first range of motion ranging from an input idle position to an input maximum position. A first linkage body is operably coupled with the input mechanism and has a second range of motion ranging from a first linkage idle position to a first linkage maximum position wherein movement of the input mechanism from the input idle position through the input maximum position correspondingly moves the first linkage body through the second range of motion from the first linkage idle position to the first linkage maximum position. A first biasing member is operably coupled to the speed control assembly for biasing the first linkage body and the user-operable input mechanism toward the first linkage idle position and the input idle position respectively. A second linkage body having a third range of motion which includes a second linkage idle position and a second linkage maximum throttle position is also provided. The second linkage body is operably coupled to the engine wherein movement of the second linkage body through the third range of motion varies the speed of the engine. Movement of the second linkage member in a first direction from the second linkage idle position toward the second linkage maximum throttle position progressively increases the speed of the engine. The second linkage body is movable relative to the first linkage body and a second biasing member biases the second linkage body relative to the first linkage body in the first direction. The second linkage body is engagable with the first linkage body whereby relative movement of the second linkage body relative to the first linkage body in the first direction is limited and wherein, as the first linkage body is moved through the second range of motion from the first linkage idle position to the first linkage maximum position, the second linkage body remains engaged with the first linkage body and is moved in the first direction until the second linkage member engages a stop which limits further travel of the second linkage member in the first direction. The first linkage body being intermediate the first linkage idle and the first linkage maximum positions when the second linkage body engages the stop. Further travel of the first linkage body toward the first linkage maximum position after the second linkage body has engaged the stop causing relative movement of the first and second linkage bodies in a direction opposed by the second biasing element.
In an alternative embodiment, the vehicle may also include a first adjustable stop mechanism operably disposed between the first linkage body and the second linkage body wherein the first stop mechanism selectively adjusts the relative positions of the first and second linkage bodies when the second linkage body is engaged with the first linkage body. The vehicle may also include a second adjustable stop mechanism operably disposed between the second linkage body and the vehicle body wherein the second stop mechanism includes the stop and selectively adjusts the extent to which the second linkage body can travel in the first direction. The first and second linkage bodies may be pivotally mounted about a common pivot axis. Additionally, the first biasing member may secured at one end to the first linkage body.
The invention comprises, in another form thereof, a vehicle having a vehicle body and an engine mounted on the vehicle body. The engine includes a governor lever coupled thereto wherein movement of the governor lever adjusts the speed of the engine. The vehicle includes a user-operated input mechanism having a first range of motion ranging from an input idle position to an input maximum position. A first linkage body is operably coupled to the input mechanism and has a second range of motion ranging from a first linkage idle position to a first linkage maximum position. A first biasing member is operably coupled to the first linkage body and biases the first linkage body toward the first linkage idle position. A second linkage body moveable through a third range of motion including a first position and a second position is operably coupled to the governor lever. Movement of the second linkage body in a first direction from the first position to the second position progressively moves the governor lever in a direction causing an increase in the speed of the engine. The second linkage body is movable relative to and engageable with the first linkage body and a second biasing member biases the second linkage body relative to said first linkage body in the first direction and toward engagement with the first linkage body. A first adjustable stop mechanism selectively adjusts the relative positions of the first and second linkage bodies when the second biasing member biases the first and second linkage bodies into engagement. The first and second linkage bodies are engagable when the first linkage body is in the first linkage idle position. A second adjustable stop mechanism is provided wherein movement of the first linkage mechanism from the first linkage idle position toward the first linkage maximum position engages the second linkage body with at least a portion of the second stop mechanism. The second stop mechanism selectively adjusts the relative positions of the second linkage body and the governor lever when the second linkage body engages said portion of the second stop mechanism. The first linkage, member is movable relative to the second linkage member to the first linkage maximum position with the second linkage body remaining engaged with said portion of the second stop mechanism.
In alternative embodiments, at least one of the first and second stop mechanisms of such a vehicle may include a threadingly adjustable member. The first and second linkage bodies may also be pivotally mounted on a common pivot member. The operable coupling of the input mechanism and the first linkage body may include the use of a bowden cable secured to the first linkage body.
The invention comprises, in yet another form thereof, a linkage assembly for a vehicle having an engine and an operator-controlled speed control input mechanism. The linkage assembly includes a mounting member securable to the vehicle, a first linkage body and a second linkage body. The first linkage body is pivotally secured to the mounting member and is movable relative to the mounting member in a range of motion extending from an idle position to a maximum position wherein movement from the idle position toward the maximum position defines a first pivotal direction. The first linkage body is adapted for operable coupling with the user-controlled input mechanism wherein the user-controlled input mechanism controls movement of the first linkage body through its range of motion. A first biasing member is operably disposed between the first linkage body and the mounting member for biasing the first linkage body with respect to the mounting member in a second pivotal direction opposite the first direction. The second linkage body is pivotally secured to the mounting member with each of the first and second linkage bodies being pivotal about a common axis. The second linkage body is adapted for operable coupling with the engine wherein movement of the second linkage body selectively adjusts the speed of the engine with movement of the second linkage body in the first pivotal direction progressively increasing the speed of the engine. A second biasing member is operably disposed between the first and second linkage bodies. The second biasing member biases the second linkage body relative to the first linkage body in the first direction. A first adjustable stop mechanism is operably disposed between the first and second linkage bodies wherein movement of the second linkage body in the first direction relative to the first linkage body is limited by the first stop mechanism. The relative positions of the first and second linkage bodies when the first and second linkage bodies are engaged being selectively adjustable by the first stop mechanism. A second adjustable stop mechanism is operably disposed between the mounting member and the second linkage member wherein movement of the second linkage body in the first direction relative to the mounting member is limited by the second stop mechanism. The relative positions of the mounting member and the second linkage body when the second stop mechanism has limited travel of the second linkage body being selectively adjustable by the second stop mechanism. As the first linkage body moves from the idle position toward the maximum position, the second linkage body remains in the relative position defined by the first stop mechanism and is moved in the first direction until the second adjustable stop mechanism limits further travel of the second linkage member in the first direction. The first linkage body is intermediate the idle position and the maximum position when movement the second linkage body is limited by the second stop mechanism and further travel of the first linkage body toward the maximum position after the second stop mechanism has limited further movement of the second linkage body causes relative movement of the first and second linkage bodies in a direction opposed by the second biasing member.
In alternative embodiments, the first and second stop mechanisms of the linkage assembly may each include a threadingly adjustable member. The first and second linkage bodies may be secured to the mounting member with a common fastener wherein the fastener defines the common pivot axis, i.e., the pivot axis of both linkage bodies. The first stop mechanism may include a first bent tab on the first linkage body, a second bent tab on the second linkage body and a threaded member secured in an opening in one of the bent tabs and engageable with the other of the bent tabs. The second stop mechanism may include a first bent tab on the mounting member, a second bent tab on the second linkage body and a threaded member secured in an opening in one of the bent tabs and engageable with the other of the bent tabs. The first biasing member may be a tension spring secured to the mounting member and the first linkage body.
The invention comprises, in another form thereof, a method of variably controlling the running speed of an engine. A user-operable input mechanism that is moveable through a first range of motion between an input idle position and an input maximum position and a linkage assembly having a first linkage body and a second linkage body are provided. The method includes operably coupling the first linkage body to the input mechanism wherein the first linkage body is moved through a second range of motion from a first linkage idle position to a first linkage maximum position as the input mechanism is moved from the input idle position to the input maximum position. The second linkage body is operably coupled to the engine wherein the position of said second linkage body controls the running speed of the engine. The second linkage body is adjustably positioned in a second linkage idle position relative to the first linkage body when the first linkage body is disposed in the first linkage idle position wherein adjustment of the second linkage idle position adjusts the idle speed of the engine. The second linkage body is operably coupled to the first linkage body wherein the second linkage body is moved from the second linkage idle position to a second linkage maximum throttle position as the first linkage body is moved from the first linkage idle position toward the first linkage maximum position and wherein movement of the second linkage body from the second linkage idle position toward the second linkage maximum throttle position progressively increases the speed of the engine. The method also includes stopping movement of the second linkage body at a selectively adjustable position defining the second linkage maximum throttle position before the input mechanism has reached the input maximum position and wherein the input mechanism is moveable to the input maximum position after stopping movement of the second linkage body at the second linkage maximum throttle position.
The method may also include biasing the second linkage body toward the first linkage body in a direction toward the second linkage maximum throttle position. Additionally, the method may include biasing the input mechanism toward the input idle position. The first linkage body may be moveable to the first linkage maximum position after stopping movement of the second linkage body at the second linkage maximum throttle position.
The invention may comprise, in yet another form thereof, a method of variably controlling the running speed of an engine. A user-operable input mechanism moveable through a first range of motion between an input idle position and an input maximum position and a linkage assembly having a first linkage body and a second linkage body are provided. The method also includes operably coupling the first linkage body to the input mechanism wherein the first linkage body is moved through a second range of motion from a first linkage idle position to a first linkage maximum position as the input mechanism is moved from the input idle position to the input maximum position. The second linkage body is operably coupled to the engine wherein the position of the second linkage body controls the running speed of the engine. The method also includes operably coupling the second linkage body to the first linkage body including (a) disposing the second linkage body in a selectively adjustable position relative to the first linkage body when the first linkage body is disposed in the first linkage idle position; (b) maintaining the second linkage body in the selected position relative to the first linkage body and moving the second linkage body in a first direction progressively increasing the speed of the engine as the first linkage is moved from the first linkage idle position toward the first linkage maximum position; and (c) stopping movement of the second linkage body in the first direction at a selectively adjustable location wherein the first linkage body is moveable relative to the second linkage body and to the first linkage maximum position after stopping movement of the second linkage body.
Maintaining the second linkage body in the selected position relative to the first linkage body may include biasing the second linkage body toward the first linkage body in the first direction. The method may also include biasing the first linkage body toward the first linkage idle position.
The method may also include biasing the second linkage body toward the first linkage body in said first direction and biasing the input mechanism toward the input idle position.
An advantage of some of the embodiments of the present invention is that it provides a linkage assembly which may be used to set or adjust the idle speed and maximum speed of the engine without restricting the motion of the user-operable input mechanism, such as a foot operated accelerator, which allows the operator to control the speed of the vehicle. The idle speed and maximum speed of the engine may be set independently of each other. It also allows the input mechanism to have a consistent feel throughout the range of its motion, i.e., the force biasing the input mechanism toward its idle position is relatively consistent throughout the range of motion of the input mechanism.
Another advantage of the present invention is that it provides a linkage assembly that may be used with a variety of existing accelerators or similar user-operable input mechanisms without requiring the modification of the accelerators.